This invention relates generally to audio transceiver units, and in particular, to a radio transceiver which may be reconfigured relatively easily from one having a display capability to a lower cost version which does not have a display.
The invention also relates to a radio transceiver construction which facilitates the incorporation or omission of a display capability during production.
For marketing and other reasons, manufacturers of radio communications devices typically offer several different configurations for each communications product manufactured. A particular model of radio transceiver may have a "basic" or minimal configuration but may optionally be provided with additional features or "options" at additional cost.
For example, a basic transceiver configuration may provide communications over a limited number of communications channels for basic radio transmitting and receiving functions required by all users. Some users may, however, have additional requirements requiring additional features--such as additional communications channels, receiver channel scanning, display capability and so on. The ability of a manufacturer to provide such additional "options" permits increases in the flexibility, versatility, desirability and range of applications of the product without penalizing purchasers of the basic configuration with increased cost. Purchasers of the basic model pay a minimum price for the minimal configuration, while users requiring additional "option" features pay an increased price based on the number and type of options required.
In the past, additional options were generally provided by incorporating additional components and circuitry into the device. For example, in the past, channel scanning capability or additional operating channels were added by installing additional frequency selection circuitry into the transceiver. Similarly, the tone activated squelch option typically required an additional tone decoder circuit to be installed. Transceiver designers used modular architectures to accommodate additional plug-in "option modules".
An example of this design approach is the prior art "MLS" series radio transceivers manufactured for General Electric Company by Japan Radio Corp. These "MLS" transceivers include basic transceiver circuitry disposed within a housing. The front . panel assembly of the transceiver housing was manufactured separately, and consists of a separable front panel "escutcheon" plate( also referred to as a control panel). Mechanically mounted to the escutcheon plate or control panel is a printed circuit board which plug-connects to the basic transceiver circuitry when the escutcheon plate is mechanically fastened to the housing. The escutcheon plate and associated printed circuit board comprises a module separable from the transceiver main housing and basic circuitry. The module includes user controls mounted on the escutcheon plate and circuitry required to connect user controls mounted on the plate to the transceiver circuitry.
Since different "option" features in many cases require different additional user controls, different models of escutcheon plate modules were produced for the "MLS" series transceivers. In particular, the "MLS" transceiver was made available in five different versions: (1) a two-channel "basic" version; (2) an 8-channel version with the scan feature; (3) a 16-channel version without scan; and (4) a 16-channel version with scan feature. Five different interchangeable escutcheon plates with different user control arrangements corresponding to these five different transceiver versions were also made. The particular escutcheon plate/control panel installed on a particular "MLS" transceiver limited the transceiver features the user could access. For example, the escutcheon plate corresponding to the "MLS" transceiver versions with 16-channel capability and no scan feature does not have a control to actuate the scan feature--preventing the user from obtaining the benefit of the scan feature. Similarly, the escutcheon plates corresponding to the 8-channel transceiver versions do not include user controls to access more than 8 channels.
Since all "MLS" transceivers included identical basic transceiver circuitry and main housing, reduced manufacturing costs and increased reliability derived from large scale manufacturing were obtained. Specific purchaser selected options could be provided in a particular unit simply by installing the appropriate escutcheon plate module--a procedure which could be performed in the field if desired. Incorporation of the circuitry performing the option functions and user controls interacting with such circuitry within the same front panel escutcheon plate module permitted a transceiver to be reconfigured by simply "unplugging" one module and "plugging in" a different module (further increasing reliability and decreasing manufacturing costs).
Commonly assigned U.S. Pat. application Ser. No. 07/183,212 filed Apr. 19, 1988 identified above discloses an improvement in which escutcheon plates need not carry additional circuitry providing additional functionality but instead carry different user control configurations and associated corresponding security circuits. The transceiver microprocessor expects a certain user control configuration based on the type of security circuit installed, and disables software-controlled transceiver functions not corresponding to the expected control configuration.
It is also generally known to load a transceiver personality EEPROM via an external connector, see, e.g., commonly assigned U.S. Pat. No. 4,525,865 to Mears and U.S. Pat. No. 4,843,588 to Flynn.
Further improvements are possible, however. Most "full-featured" digital radio transceivers nowadays include an alphanumeric display (e.g., an LCD display panel) because of the variety of different information that must be displayed. Transceivers in the past needed only to display a few indications (e.g., channel number, on/off status and transmit/receive status). Modern digital "programmable" transceivers offering advanced, user-configurable features such as DTMF dialing with a stored telephone number list, selection between different operating modes, and scanning of user-selectable channel numbers. Such modern transceivers by necessity must provide informative displays--for the user otherwise would become "lost" in the user interface provided by the transceiver and could not effectively "program" his selections. The additional flexibility and power provided by such advanced communications functions (and the "user-friendly" invocation of such functions using an alphanumeric display panel) have become absolutely essential in many communications applications. It is now, for example, possible to equip a police supervisor with a handheld radio transceiver offering critical features, functionally and flexibility not even available to many main dispatchers only a few years ago. This additional communications flexibility permits a public service force to respond more rapidly and efficiently to emergency situations.
On the other hand, some users only require relatively limited functionality from their radio transceivers and would only be confused by (or are not willing to pay for) additional features. An LCD display assembly is a rather costly component and therefore substantially increases the price of a radio transceiver. It has become difficult to design a full featured transceiver without a display for most applications, because many users now demand and require a display and the associated functionality it facilitates.
It is an important object of this invention to provide a radio transceiver design which facilitates production and/or which permits quick conversion of an otherwise standardized transceiver design from one which includes a display to one which does not have a display.
In accordance with one aspect of the present invention, a standardized radio transceiver can be produced with all of the internal circuitry and components (and associated functionality) required . for a full-featured premium model with the available optional features incorporated therein, including an electronic display, such as, for example, an LCD or LED display. This premium model includes a housing formed with a display port, an internal display board and an associated display escutcheon plate. To produce a lower cost version, or to convert this model to a lower cost version having no display capability, all that is required is to remove (or not install) the display board and display escutcheon plate, and replace the latter with (or install as an original component) a blank escutcheon plate (preferably plastic). Since the display board is connected to a main controller board by a conventional flex interconnect (or other modular connector), the display board is easily removed (or omitted), while retaining substantially full operational use of the main controller board (without the display).
In accordance with a further aspect of the present invention, removal (or omission) of the display components is automatically sensed by the transceiver's internal microprocessor. If the microprocessor senses the display components are present, it operates in a mode providing a display interface and associated additional functionality. If, on the other hand, the microprocessor senses the display components are absent (or have failed), the transceiver could be enabled to operate in a different mode which provides less functionality not requiring a display interface. Thus, identical transceiver main controller circuitry can be used for transceiver versions with display components and for transceiver versions without display components. This has the advantage of allowing for a lower cost version of an otherwise standard transceiver to be built using common parts (controller board, mechanical housing, FR section, etc.)--and perhaps more importantly, using identical controller circuitry and programming, merely by removing or not installing the display board. Only one version of the controller circuitry needs to be manufactured, since this circuitry automatically adapts to the presence or absence of display components. Only a few simple operations on the manufacturing floor (e.g., install or not install a display board) are required to provide different transceiver versions with completely different functionalities and characteristics.
It is thus a further feature of the invention that the microprocessor based controller hardware is designed to allow operation with or without a display, and the microprocessor senses when no display is present to determine that the radio is of a certain type, i.e., a non-display version.
It is another feature of the invention that in the event a different keypad and control panel is to be used in a non-display version of the transceiver, these elements are likewise easily changed to suit the customer's requirements.
In one exemplary embodiment, a display board incorporating the display unit, display driver IC and other supporting components, is mounted to an interior surface or back side of a front cover of the transceiver housing. The display board is secured by four screws which are inserted from the interior of the housing cover, and which extend through holes in the cover into threaded bores formed in the display escutcheon plate. It will thus be appreciated that by removing these screws, both the display board and the display escutcheon plate may be separated from the transceiver unit front cover. The display board may then be separated from the main controller board by disconnecting the flex interconnect. Upon fastening a blank escutcheon plate over the display area or port of the front cover, using four screws, the reconfiguration to a non-display version is completed.
In the event a different front control panel is also required for the reconfiguration procedure, interchangeable panels are provided for quick connect/disconnect from the transceiver housing. The manner in which this is accomplished is the subject of commonly owned copending application Ser. No. 07/390, 254, filed concurrently herewith, the subject matter of which is incorporated herein by reference.
Additional objects and advantages of the invention will become apparent from the detailed description which follows.